Huge pages

[Tiago Stürmer Daitx]

On Wed, 2013-04-10 at 19:26 +0200, Volker Simonis wrote:
> 
> I've attached a small patch for you, which should enable UseHugeTLBFS
> on our Linux/PPC port (i.e. you should be able to use -XX:
> +UseHugeTLBFS -XX:+UseLargePages) with and without compressed
> pointers.

The patch works and seems to give a bit better performance than
hugepages through shm... but still only for maximum heaps of 1984
megabytes. I saw around 5% better run times with UseHugeTLBFS, while
UseSHM was around 4% better. This is kind bellow the jitter I see
sometimes, so don't take it for granted until I repeat the tests a
significant amount of times.

The problem is that any heap bigger than 1984m gives ~7% worse
performance compared to _not_ using hugepages - there was no performance
loss when using shm.

Please let me know how else I can help. =)

Regards,
Tiago Daitx

-- 
Tiago Stürmer Daitx
tdaitx at linux.vnet.ibm.com
IBM - Linux Technology Center